Tumor immune microenvironment (TIME) to enhance antitumor immunity.

The tumor microenvironment is a result of dynamic interaction between different cellular and non-cellular components. In its essence it is not a solo performer, but an ensemble of performers that includes cancer cells, fibroblasts, myo-fibroblasts, endothelial cells and immune cells. The short review highlights important immune infiltrates within the tumor microenvironment that shape cytotoxic t lymphocyte (CTL)-rich immune hot and CTL-deficient immune cold tumors and novel strategies that have potential role in enhancing our immune responses in both immune hot and immune cold tumors.

[Reactive oxygen species mediate the injury and deficient hematopoietic supportive capacity of umbilical cord derived mesenchymal stem cells induced by iron overload].

OBJECTIVE: To explore the effects of iron overload on umbilical cord derived mesenchymal stem cells (UC-MSC) and elucidate the involvement of reactive oxygen species (ROS) in this process. METHODS: The iron overload model of MSC was established by in vitro addition of ferric ammonium citrate (FAC) into culture medium. Cell proliferation and apoptosis were determined by Annexin V/PI double staining and population doubling time (DT) respectively. Co-culture system was used to assess the hematopoietic support capacity of UC-MSC in different groups. Thereafter the ROS level was detected with fluorescent probe 2', 7'-dichlorofluorescin diacetate (DCFH-DA). And the ROS related signaling factors of p-p38MAPK, p38 MAPK, P53 were measured by Western blot. RESULTS: (1) The DT of UC-MSC in iron overload group was significantly longer than that of control ((24.43 ± 2.72) h vs (16.03 ± 2.31) h, P < 0.05). But the difference was insignificant after two passages (P > 0.05). (2) Apoptosis in iron overload group was higher than that of control (12.75% ± 0.32% vs 3.63% ± 0.80%, P < 0.05). (3) The colony forming capacity of mononuclear cell (MNC) co-cultured with UC-MSC of iron overload group for 1/2 weeks significantly decreased. (4) The ROS level of UC-MSC with iron overload was higher than that of control in time and concentration-dependent fashions and it peaked at 400 µmol/L of FAC for 12 h (1499 ± 86 vs 548 ± 97, P < 0.05). (5) The expressions of p-p38MAPK and P53 increased in response to FAC compared with control. But such an effect was partially inhibited after the use of antioxidants. CONCLUSIONS: Iron overload may impair the proliferation, survival and hematopoiesis supportive function of UC-MSC by enhancing the generation of ROS. And ROS stimulates the signaling pathways of p-p38MAPK and P53.

Free iron catalyzes oxidative damage to hematopoietic cells/mesenchymal stem cells in vitro and suppresses hematopoiesis in iron overload patients.

OBJECTIVES: Transfusional iron overload is of major concern in hematological disease. Iron-overload-related dyserythropoiesis and reactive oxygen species (ROS)-related damage to hematopoietic stem cell (HSC) function are major setbacks in treatment for such disorders. We therefore aim to investigate the effect of iron overload on hematopoiesis in the patients and explore the role of ROS in iron-induced oxidative damage in hematopoietic cells and microenvironment in vitro. PATIENTS AND METHODS: The hematopoietic colony-forming capacity and ROS level of bone marrow cells were tested before and after iron chelation therapy. In vitro, we first established an iron overload model of bone marrow mononuclear cells (BMMNC) and umbilical cord-derived mesenchymal stem cells (UC-MSC). ROS level, cell cycle, and apoptosis were measured by FACS. Function of cells was individually studied by Colony-forming cell (CFC) assay and co-culture system. Finally, ROS-related signaling pathway was also detected by Western blot. RESULTS: After administering deferoxamine (DFO), reduced blood transfusion, increased neutrophil, increased platelet, and improved pancytopenia were observed in 76.9%, 46.2%, 26.9%, and 15.4% of the patients, respectively. Furthermore, the colony-forming capacity of BMMNC from iron overload patient was deficient, and ROS level was higher, which were partially recovered following iron chelation therapy. In vitro, exposure of BMMNC to ferric ammonium citrate (FAC) for 24 h decreased the ratio of CD34(+) cell from 0.91 ± 0.12% to 0.39 ± 0.07%. Excessive iron could also induce apoptosis, arrest cell cycle, and decrease function of BMMNC and UC-MSC, which was accompanied by increased ROS level and stimulated p38MAPK, p53 signaling pathway. More importantly, N-acetyl-L-cysteine (NAC) or DFO could partially attenuate cell injury and inhibit the signaling pathway induced by excessive iron. CONCLUSIONS: Our study shows that iron overload injures the hematopoiesis by damaging hematopoietic cell and hematopoietic microenvironment, which is mediated by ROS-related signaling proteins.

[Effects and mechanism on anti-leukemic activity of cytokine-induced killer cells with an endogenous expression of interleukin-21].

OBJECTIVE: To explore the effects and mechanism on anti-leukemic activity of cytokine inducing killer (CIK) cells with an endogenous expression of interleukin-21 (IL-21). METHODS: Mononuclear cells were isolated from peripheral blood and cultured with cytokines to generate CIK cells. IL-21 lentiviral vector was constructed and used to transfect 293T cells. Then the culture supernatant with virus infected CIK cells was identified. Proliferation of CIK cells and their cytotoxic activity against K562 cells were measured by methyl thiazolyl tetrazolium (MTT). The expressions of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), tumor necrosis factor-ß (TNF-ß), perforin, granzyme A, granzyme B, FasL and NKG2D mRNA were measured by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). Immunophenotypes of CIK cells, IL-21 receptor (IL-21R) and FasL on the surface of CIK cells, intra-cellular perforin and granzyme B of CIK cells were measured by flow cytometry. And the concentrations of IFN-γ and TNF-α in cultured supernatant were measured by enzyme immunoassay. RESULTS: By restriction enzyme digestion and sequencing, IL-21 lentiviral vector was identified, after transfecting virus supernatant into CIK cells, the expression of IL-21 was detected in CIK cells. Compared to control, (1) the total number of cells remained unchanged, but the proportion of cells expressing CD3(+)/CD56(+) phenotype increased from 16.95% ± 4.70% to 24.60% ± 2.10%. (2) Cytotoxic activity against K562 cells by CIK cells increased from 23.3% ± 2.8% to 58.4% ± 8.3% and stayed at 61.2% ± 6.2% after 5 days. It was stronger and longer compared to the exogenous effect of IL-21 (from 22.8% ± 2.8% to 44.6% ± 8.3%). (3) The expression of IL-21R increased around 2 folds. (4) The mRNA expressions of IFN-γ and TNF-α increased almost 1.5 folds, perforin, granzyme B, FasL rose almost 2 folds, the expressions of granzyme A, TNF-ß and NKG2D were similar with those of controls. (5) Detected by flow cytometry, the expression of FasL of CIK cells was higher than that of control (0.56% ± 0.37% vs 0.06% ± 0.02%), the expression of perforin increased from 12.23% ± 2.35% to 25.86% ± 6.13%, the expression of granzyme B rose from 14.56% ± 1.36% to 37.58% ± 2.30%, the concentration of IFN-γ in culture supernatant spiked from (23.2 ± 5.6) to (55.3 ± 3.5) ng/L and TNF-α jumped from (5.6 ± 0.6) to (15.6 ± 0.6) µg/L. CONCLUSIONS: CIK cells with an endogenous expression of IL-21 have stronger anti-leukemic activity through an up-regulation of IL-21R, perforin, granzyme B, FasL, IFN-γ and TNF-α. Thus IL-21 may potentially enhance the anti-leukemic immunotherapy.

[Effects of humanized interleukin 21 on anti-leukemic activity of cytokine induced killer cells and the mechanism].

OBJECTIVE: To explore the effects of humanized interleukin 21 (IL-21) on anti-leukemic activity of cytokine induced killer(CIK) cells derived from peripheral blood(PB) and the mechanism. METHODS: Mononuclear cells were separated from peripheral blood and cultured with cytokines to induce CIK cells. Proliferation of CIK cells with or without IL-21 stimulation and their cytotoxic activity against K562 cells was measured by MTT method. IL-21 receptor (IL-21R) and immunophenotypes of CIK cells were measured by flow cytometry. The expression of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), tumor necrosis factor-ß (TNF-ß), perforin, granzyme A, granzyme B, FasL and NKG2D mRNA were measured by semi-quantitative RT-PCR. FasL on the surface of CIK cells and intra-cellular perforin and granzyme B of CIK cells were measured by flow cytometry. The concentration of IFN-γ and TNF-α in the cultured supernatant were measured by enzyme immunoassay. JAK-STAT signalling pathway of CIK cells were measured by Western-blot. RESULTS: After IL-21 stimulation, the proportion of CIK cells increased from (17.5 ± 4.7)% to (26.5 ± 2.1)%. Cytotoxic activity against K562 cells by CIK cells increased from (22.8 ± 2.8)% to(44.6 ± 8.3)%. The expression of IL-21R increased about 2 folds. The mRNA expression of IFN-γ increased almost 2 folds from (0.3760 ± 0.2358) to (0.7786 ± 0.2493), TNF-α increased almost 2 folds from (0.6557 ± 0.1598) to (1.3145 ± 0.2136), perforin increased almost 1.5 folds from (0.6361 ± 0.1457) to (0.9831 ± 0.1265), granzyme B increased almost 2 folds from (0.4084 ± 0.1589) to (0.7319 ± 0.1639), FasL increased almost 2 folds from (0.4015 ± 0.2842) to (0.7381 ± 0.2568), the expression of granzyme A, TNF-ß and NKG2D were similar with control. Flow cytometry analysis showed that the expression of FasL of CIK cells was higher than that of control (0.19% vs 0.04%), the expression of perforin increased from 35.28% to 53.16%, and the expression of granzyme B increased from 43.16% to 78.82%. The concentration of IFN-γ in the culture supernatant increased almost 2 folds from (25.8 ± 6.1) ng/L to (56.0 ± 2.3) ng/L, and TNF-α increased almost 3 folds from (5.64 ± 0.61) µg/L to (15.14 ± 0.93) µg/L. Western blot showed that the expression of STAT1 and STAT5a had no significant differences, but the expression of STAT3 and STAT5b were higher than that of control. CONCLUSION: Humanized IL-21 could enhance the anti-leukemic activity of CIK cells via increasing IL-21R, perforin, granzyme B, FasL, IFN-γ and TNF-α, as well as activating JAK-STAT signaling pathway. These data indicate that IL-21 has a potential clinical value in the enhancement of anti-leukemic immunotherapy.